Wind power is considered one of the cleanest, most environmentally friendly energy sources presently available, and wind turbines have gained increased attention in this regard. A modern wind turbine typically includes a tower, generator, gearbox, nacelle, and one or more rotor blades. The rotor blades capture kinetic energy of wind using known foil principles. The rotor blades transmit the kinetic energy in the form of rotational energy so as to turn a shaft coupling the rotor blades to a gearbox, or if a gearbox is not used, directly to the generator. The generator then converts the mechanical energy to electrical energy that may be deployed to a utility grid.
In many cases, accessory components are attached to the rotor blades of wind turbines to perform various functions during operation of the wind turbine. For example, it is known to change the aerodynamic characteristics of wind turbine rotor blades by adding protrusions or other structures to the surface of the blade in order to increase the energy conversion efficiency during normal operation of the wind turbine by increasing the lift force of the blades while decreasing the drag force. Such components include, for example, winglets, tip extensions, and vortex generators. The purposes and operational principals of these devices are well understood by those skilled in the art.
The installation techniques and systems for attaching conventional add-on components can be expensive and time consuming, particularly for field installations. For example, typical field installation techniques require the use of attachment fixtures and significant dwell time for curing the attachment adhesives. The adhesives typically are considered hazardous materials and appropriate precautions and protective measures (both equipment and personal) must be taken. In addition, the smearing of liquid or past adhesives while pushing the add-on components into place can result in inconsistent and unpredictable results, particularly for tip extension add-ons that are pushed onto the tip end of an existing blade in the field.
Especially for the addition of tip extensions, the prevalent conventional method involves cutting off the existing blade tip so as to integrate the extension with internal blade structure. This process is time consuming, expensive and has the risk of damage to the main blade structure.
The industry has recognized that double-sided strain isolation tapes offer substantial benefits for attaching add-on components, but the use of such tapes has proven to be challenging to precisely install the components (especially larger components) due to the instant bond once the tape makes contact with a mating surface. Repositioning of the part can be difficult, if not impossible.
U.S. Pat. Pub. No. 2014/0328692 describes a vortex generator accessory that is mounted to either of the suction side or pressure side of a wind turbine blade and includes a base portion and a protrusion member extending upwardly from the base portion. An attachment layer connects the base portion to the suction or pressure side. The attachment layer has a lower shear modulus than the base portion to allow for shear slippage between the base portion and the underlying suction or pressure side. The attachment layer may be a foam-based strip member with adhesive on opposite interface sides thereof. For example, this attachment layer may be Very High Bond (VHB™) or SAFT (Solar Acrylic Foam Tape) foam-based strip material.
Thus, the industry is continuously seeking improved methods for installing add-on components to wind turbine blades in a fast and low-cost operation that also provides for a repositioning opportunity to ensure accurate add-on component placement.